||BACKGROUND: Previous studies of platelet al/ele frequencies
in Sub-Saharan African population~nabled
us to identity discrepancies in HPA-3 typing, suggesting
the presence of new mutations and of a greater polymorphism
than 50 far described in other populations.
OBJECTIVES: To analyze these discrepancies and to
0sess the factors leading to potential alloimmunization
.. 1 these populations.
f'ATERIALS AND METHODS: Samples: Matemal
samples from a Beninese woman following in utero
death and panels of blood donors from Benin,
Cameroon, Congo, and Pygmies from Central Africa.
Techniques: Genotyping was performed using polymerase
chain reaction-restriction fragment length polymorphism
(PCR-RFLP), PCR-sequence specifie primers
(PCR-SSP) and sequencing techniques.
RESULTS: Three new mutations were found on GPllb
gene: exon 26 a) 2614C>A situated belween HPA-3
and HPA-9w, b) 2645C>T downstream of HPA-3,
c) intron 26 IVS26+89G>A. These mutations may lead
to discrepant DNA typing results, due either to a localization
in the complementary sequence r8cognized bl
the primer or to the appearance of a new enzyme
restriction site. Furthermore, a bilaterallinkage « deletion
(.19 bp) intron 21 and the HPA-3b allele (exon 26)
f""\> fO!Jnd in Caucasian, Asian, and Oceanian populaHions
is not found in African populations, suggesting that
f ts appearance was prior to HPA-3.
CONCLUSION: Three new mutations have been identified,
two of them potentially irnmunogenic through their
position. Furthermore, the polymorphism found on
intron 26, localized in'the complementary sequence of
the PCR primer, may lead to a false typing assignation.
It is therefore important to diversify techniques, both
genomic (PCR-RFLP and PCR-SSP), and proteomic
monoclonal antibody-specitic immobilization of platelets
antigen (MAIPA) to ensure accurate HPA antigenic